1. Field of the Invention
The present invention relates to: a semiconductor device having a sealing function added to a vent path provided at a covering body for covering a semiconductor element; a manufacturing method of the semiconductor device; and a module for an optical device which uses the semiconductor device.
2. Description of Related Art
A conventional photo acceptance semiconductor device, such as a CCD (Charge Coupled Device) image sensor and a CMOS (Complementary Metal Oxide Semiconductor) image sensor, for converting an optical signal into an electric signal has a semiconductor element or the like packaged and sealed in a hollow package made of ceramics, plastics or the like, in order to prevent moisture, contaminant and the like from entering the semiconductor element from the outside.
FIG. 1 is a sectional view showing the schematic structure of a solid-state imaging device as an example of a conventional photo acceptance semiconductor device. The solid-state imaging device shown in FIG. 1 comprises a hollow package having a hollow portion (space) formed between a base 50 provided with a recess 52 formed at a substantially center portion thereof and a transparent covering portion 4 attached via a frame 53 on the base 50, and a solid-state imaging element 2 is arranged at this hollow portion. At the base 50 made of ceramics, plastics or the like, the solid-state imaging element 2 is laid in the recess 52 and a lead member 51 which extends from a peripheral portion of the base 50 toward the outside is attached. The lead member 51 made of 42-alloy, copper or the like and the solid-state imaging element 2 are electrically connected via bonding wire 2w. 
The frame 53 having a predetermined height is attached immediately above the lead member 51 and the covering portion 4 made of glass or the like is implanted in a notch portion of this frame 53. Adhesive 54 is used for bonding the frame 53 with the covering portion 4 to seal the hollow portion between the base 50 and the covering portion 4. By sealing the hollow portion between the base 50 and the covering portion 4, the structure prevents moisture, contaminant and the like from entering the solid-state imaging element 2 from the outside. Furthermore, the adhesive 54 is filled in the hollow portion so as not to block an optical path between an effective pixel area 3 and the covering portion 4.
Moreover, in a conventional manufacturing method of a solid-state imaging device shown in FIG. 1, a plurality of solid-state imaging elements 2 which are formed simultaneously on a semiconductor wafer are divided and dissected out with a dicing saw or the like, a dissected-out solid-state imaging element 2 is laid on the base 50 and then the covering portion 4 is placed so as to cover the entire solid-state imaging element 2, or even including other portion.
Regarding the package form of the solid-state imaging device shown in FIG. 1, however, it is necessary to select the adhesive 54 and the material and the form of the frame 53 and the base 50 to prevent moisture from entering the inside of the solid-state imaging device (hollow portion) as much as possible in order to prevent humidity deterioration of the solid-state imaging element 2 and dew formation on the inner surface of the covering portion 4, and air in a sealed portion expands or the like causing generation of air bubble or an air path between the covering portion 4 and the adhesive 54 while covering the effective pixel area 3 of the solid-state imaging element 2 with the covering portion 4. Accordingly, the adhesive 54 and the material and the form of the frame 53 and the base 50 are limited to a particular kind and, therefore, the package becomes extremely expensive and, therefore, a solid-state imaging device comprising the package also becomes expensive.
Consequently, disclosed in Japanese Patent Application Laid-Open No. 2002-124589 is a semiconductor device in which a semiconductor element is sealed in a hollow package having an air-permeable portion, so as to prevent dew formation by conforming the environment in the semiconductor device to outside air instead. FIGS. 2A and 2B are explanatory views showing the structure of a conventional semiconductor device disclosed in Japanese Patent Application Laid-Open No. 2002-124589 and, in particular, FIG. 2A shows a plan view and FIG. 2B shows a sectional view along the line B-B in FIG. 2A.
In the semiconductor device shown in FIGS. 2A and 2B, a hollow package, or a package body 55, which is made of resin, ceramics or the like and has a plurality of lead members 51 extending from and formed integrally with the package is provided, a semiconductor element, e.g. a solid-state imaging element such as a CCD or a semiconductor chip 56 such as a semiconductor laser element, is arranged inside the package body 55, metal wire (for example, gold Au wire) 57 connects an inner lead portion 5la of the lead member 51 with an electrode of the semiconductor chip 56, an opening portion of the package body 55 on the photo acceptance side is sealed with a sealing glass member, or a transparent glass plate 58, via the adhesive 54 and a hollow package 59 is composed of the glass plate 58 and the package body 55 constructed to provide this sealing portion with air permeability.
For providing an air-permeable structure, a portion which is not coated with the adhesive 54 is provided deliberately at a part of a bond portion of the package body 55 and the glass plate 58. This uncoated portion configures an air-permeable vent path 70, and air communication between the inside of the package 59 and the outside is realized through the vent path 70.
In the semiconductor device disclosed in the Japanese Patent Application Laid-Open No. 2002-124589 which has a simple linear vent portion, however, problems may occur.
That is, since the vent path 70 provided at the semiconductor device disclosed in Japanese Patent Application Laid-Open No. 2002-124589 has a simple linear form, i.e. a form extending linearly, water may enter the device through the vent path 70 in a washing step, foreign matter may enter the device together with the water, the foreign matter may attach as dust to the surface of the principal plane of the semiconductor chip 56 and scars may be generated on the surface of the principal plane of the semiconductor chip 56.